United States Air and Radiation EPA420-F-97-016
Environmental Protection October 1997
Agency
Office of Mobile Sources
&EPA Regulatory
Announcement
New Emission Standards For Heavy-
Duty Diesel Engines Used In Trucks
And Buses
The Environmental Protection Agency (EPA) is adopting a new
combined emission standard for oxides of nitrogen (NOx) and
hydrocarbons (HC) for model year 2004 and later heavy-duty diesel
engines used in trucks and buses. The new standard represents a 50
percent reduction in NOx from the 1998 and later model year NOx
standard, and will significantly assist states in meeting and maintaining
the ozone National Ambient Air Quality Standards.
What Are the Health and Environmental Benefits?
The new rule requires engines manufactured in 2004 and later model
years to have about a 50 percent lower NOx level compared to engines
meeting the 1998-2003 model year NOx standard. In 2020, EPA projects
a reduction of 1.1 million tons per year in ozone precursors due to the
new standard. In addition, the reduction in NOx emissions will also
result in a reduction of secondary nitrate particulate matter (PM) (which
forms in the atmosphere when NOx combines with ammonia) of about
43,000 tons per year.
NOx is a major contributor to the formation of ground-level ozone. The
new standard will benefit public health because ozone exposure causes a
range of human pulmonary and respiratory health effects, including chest
pain, coughing, and shortness of breath. In addition to ground-level
ozone, the secondary impacts of NOx include the formation of nitrate
PM, acid rain, and eutrophication of coastal waters. Therefore, reduc-
tions in NOx emissions will have considerable benefits to both public
health and the environment.
> Printed on Recycled Paper
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How Much Will the Final Rule Cost?
EPA estimates a near term retail price increase of $260-$470 per vehicle,
with costs decreasing to half that amount in five years. The near term
increase represents a 2 to 4 percent increase in engine price and less than
one percent of the price of most new heavy-duty vehicles. EPA does not
expect any increase in fuel consumption due to the new rule. The long
term cost effectiveness of the final rule is estimated to be $100-$200 per
ton of NOx plus HC.
How Will the Rule Assist States?
The significant reduction in NOx emissions expected from the new
standard will assist the states in meeting the National Ambient Air
Quality Standards for ozone and PM. NOx emission inventories are
projected to rise by the early 2000s due to continued industrial growth
and expansion of motor vehicle usage. This is expected to result in a
significant increase in ground-level ozone and PM. Without further
controls, within the next 20 years mobile sources will contribute to about
half of all NOx emissions, with highway heavy-duty engines (HDEs)
representing about a quarter of these mobile source NOx emissions.
Therefore, further NOx control from HDEs on a national scale is seen as
a cost-effective strategy to control ozone levels especially where ozone
is high over a large region (as in the Midwest and Northeast).
How Does the Rule Provide Flexibility to Industry?
The final rule provides flexibility to the industry in three main areas:
• Manufacturers can certify their engines to either of two options;
• The time frame for this standard allows for the difficult technological
hurdles to be addressed without large increases in engine costs,
resulting in what EPA believes will be an extremely cost-effective way
of making necessary air quality gains; and
• The flexibility provided by averaging, banking, and trading (ABT)
lowers the costs to manufacturers and makes it easier to meet the
technical challenges of lower standards.
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In addition, engine manufacturers benefit from national emission stan-
dards because a single set of emission requirements applying to engines
in trucks and buses used anywhere in the country allows manufacturers
to achieve economies of scale and to concentrate research and develop-
ment resources most effectively.
How Did This Initiative Evolve?
In response to the need for additional pollution reduction measures at the
national level, EPA held a series of discussions with the California Air
Resources Board (CARB) and representatives of the HDE manufactur-
ing industry to exchange views on the appropriateness and feasibility of
new emission standards for HDEs. Based on these discussions, a historic
Statement of Principles (SOP) regarding highway HDEs was signed by
these parties in July 1995. EPA issued an Advance Notice of Proposed
Rulemaking (ANPRM) on August 31, 1995, which requested comment
on the SOP and the Agency's plans to formally propose new HDE
emission standards consistent with the SOP. EPA formally proposed the
standard on June 27, 1996. During the comment period for the
rulemaking, stakeholders continued their strong support for the new
standards.
What are the Main Components of the Final Rule?
Emission The standard is in the form of combined non-methane hydrocarbons
Standard (NMHC) plus NOx and is presented in units of grams emitted per brake
horsepower-hour (g/bhp-hr). It applies to diesel engines manufactured
for model years 2004 and later. Manufacturers have the choice of certify-
ing their engines to either:
2.4 g/bhp-hr NMHC + NOx or
2.5 g/bhp-hr NMHC + NOx with a limit of 0.5 g/bhp-hr on NMHC
EPA also proposed the above standard for gasoline-fueled engines, but is
not finalizing the standard at this time. The Agency is continuing to
evaluate new standards for gasoline-fueled engines and is planning a
supplemental rulemaking to address gasoline-fueled engines specifically.
In-Use EPA is adopting provisions to further encourage engine manufacturers to
Emission use emission controls that will have a high degree of durability, and will
Controls perform well in use without an unreasonable degree of owner involve-
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ABT
Provisions
Technology
Review
ment. EPA is finalizing other basic provisions to help encourage the
maintenance and repair of emission controls after the end of regulatory
life is reached, and ensure emission controls are addressed properly
during engine rebuilding.
EPA is finalizing changes to the ABT provisions to enhance the feasibil-
ity and cost-effectiveness of the standards and encourage the early
introduction of cleaner engines, thus securing emission benefits earlier
than would otherwise be the case.
A technology review will be undertaken in 1999 to assess industry
progress and propose changes in the standards if necessary. The potential
role of fuels in achieving low HDE emissions is being evaluated now as
part of a technical working group comprised of representatives from
EPA, the engine manufacturers, the oil industry and other stakeholders.
The results of these technical evaluations will be considered as a part of
the 1999 technology review.
Does the New Standard Affect Trucks and Buses
Already on the Road?
No. The new standard and related provisions only apply to 2004 and
later model year engines.
How Can I Obtain a Copy of the Final Rule?
Additional information can be obtained electronically via the EPA
Internet server on the World Wide Web at:
http://www.epa.gov/OMSWWW
Information is also available by calling the NOx/ PM Heavy-Duty
Engine voice mailbox at: 313-741-7887
or by writing to:
U.S. Environmental Protection Agency
Office of Mobile Sources
Highway Heavy-Duty Team
2565 Plymouth Road
Ann Arbor, Michigan 48105
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